1. Field of the Invention
The present invention relates to a probe chip and a probe card which are used in an electrical test of LSI. The probe chip and the probe card are placed between LSI under test (DUT; Device under Test) which is formed on a semiconductor wafer and a tester for LSI (LSI tester), to supply DUT with power for driving a circuit, ground which acts as a standard of voltage and signals to test the circuit and to convey responding signals in response to the test signals from DUT to the LSI tester. More specifically, the present invention relates to a new probe chip which is easily replaceable with another one and is a type of narrow pitch, and relates to a new probe card using the new probe chip.
2. Description of the Prior Art
An average conventional probe card is disclosed in the Japanese Patent Publication No. HEI8-64646 A (Prior Art 1). That is, in the conventional probe card in the prior art reference, probe pins made of metal such as tungsten are fixed to a pedestal (fixing ring) made of ceramic etc. in a predetermined pitch. One end of the pin is a free end (this free end contacts to a pad on the DUT) and the other end is soldered to a metal wiring on a circuit board.
The probe card is mounted on a prober to test the DUT formed on a semiconductor wafer. The free end of the probe pin is contacted to a predetermined pad on the DUT by a driving mechanism of the prober. When the free end of the probe pin contacts with the pad of the DUT, power for driving the circuit, ground which acts as a standard of voltage and signals to test the circuit are supplied from the LSI tester to the DUT and a responding signal in response to the test signals are conveyed from the DUT to the LSI tester.
In general, a plurality of DUTs are formed on a wafer so that the above-mentioned operation should be repeated in order to test all DUTs on the wafer. Therefore, it is necessary for the probe pin to make repeated contact with the pads on the DUT. Due to the repeated contact, the probe pin tends to be deformed, contaminated or broken at its front edge due to the difference in height of the pads, the existence of foreign material on the pads etc. In addition, the probe pin is also worn by the repeated contact with the metal pads because the probe pin is also made of metal.
If the front edge of the probe pin is deformed or contaminated, a contact resistance between the probe pin and the pad increases, being unable to carry out accurate testing so that it is necessary to repair or replace the damaged probe pin with a new one. Further, an arrangement of the pad on the DUT is different from one kind to another. Therefore, the arrangement of the probe pin on the probe card should be changed based on the kind of the DUT. Accordingly, the probe card should be replaced with another one when another kind of DUT is tested.
Furthermore, the Japanese Patent Publication No. HEI08-313557 A (Prior Art 2) discloses art to solve the problem in the Prior Art 1. The patent discloses a probe block in which a crank shaped probe pin is fixed on a base. One end of the crank-shaped probe pin is elastically contacted to an output terminal of TAB (Tape Automated Bonding). And a probe block is detachably attached to the base of the prober. Accordingly, at the time of replacement of a probe pin with another one, repairing of a probe pin, or changing of the arrangement of probe pin at the time of using another type of DUT can be done by replacing the probe block with another one.
However in the conventional probe card, the probe pin is fixed to the pedestal and the probe pin is fixed to the circuit board by way of soldering. Therefore, the whole set of probe card should be removed from the prober in case where the probe pin is repaired or replaced. In addition, fixing of the probe pin on the pedestal, soldering of the probe pin on the circuit board and adjusting the height of the front edge of the probe pin are all carried out manually, so that the cost of the probe card increases with the increase in the number of the probe pin. Furthermore, long time is required for repairing and replacement of the probe card, resulting in deterioration in the efficiency of the LSI testing. As mentioned above, the probe pin is made from metal needle so that a certain thickness is required. In other words, if the thickness of the probe pin is under the certain level, a desired weight can not be applied on the free end when the free end is contacted to the pad, being unable to lower the contact resistance. Accordingly, narrow-pitch narrower than a certain level can not be attained as long as metal needles are used as the probe pins.
In the Prior Art 2, a probe block is disclosed. And repairing and replacement of the probe pin and changing of the probe-pin arrangement can be carried out, but the pedestal on which the crank-shaped probe pin is fixed should be made of insulating material such as ceramic etc. In addition, a surface on which the crank-shaped probe pin is fixed should be formed to have an inclined surface. Generally it is difficult to get a desired shape with high accuracy when ceramic material is used. Even if this is possible, long time is still required for the processing. Producing a narrow-pitch type is also difficult as long as the crank-shaped probe pin is made of metal as explained above.